Correale Jorge, Farez Mauricio, Gilmore Wendy
Department of Neurology, Raúl Carrea Institute for Neurological Research, Buenos Aires, Argentina.
CNS Drugs. 2008;22(3):175-98. doi: 10.2165/00023210-200822030-00001.
Multiple sclerosis (MS) is an inflammatory demyelinating disease of the CNS, characterized pathologically by a perivascular infiltrate consisting predominantly of T cells and macrophages. Although its aetiology remains unknown, several lines of evidence support the hypothesis that autoimmune mechanisms play a major role in the development of the disease. Several widely used disease-modifying agents are approved for the treatment of MS. However, these agents are only partially effective and their ability to attenuate the more progressive phases of the disease is not clear at this time. Therefore, there is a need to develop improved treatment options for MS. This article reviews the role of several novel, selective vaccine strategies that are currently under investigation, including: (i) T-cell vaccination (TCV); (ii) T-cell receptor (TCR) peptide vaccination; (iii) DNA vaccination; and (iv) altered peptide ligand (APL) vaccination. The administration of attenuated autoreactive T cells induces regulatory networks to specifically suppress pathogenic T cells in MS, a strategy named TCV. The concept of TCV was based on the experience of vaccination against aetiological agents of infectious diseases in which individuals are purposely exposed to an attenuated microbial pathogen, which then instructs the immune system to recognize and neutralize it in its virulent form. In regard to TCV, attenuated, pathogenic T cells are similarly used to instruct the immune system to recognize and neutralize disease-inducing T cells. In experimental allergic encephalomyelitis (EAE), an animal model for MS, pathogenic T cells use a strikingly limited number of variable-region elements (V region) to form TCR specific for defined autoantigens. Thus, vaccination with peptides directed against these TCR structures may induce immunoregulatory mechanisms, thereby preventing EAE. However, unlike EAE, myelin-reactive T cells derived from MS patients utilize a broad range of different V regions, challenging the clinical utility of this approach. Subsequently, the demonstration that injection of plasmid DNA encoding a reporter gene into skeletal muscle results in expression of the encoded proteins, as well as in the induction of immune responses in animal models of autoimmunity, was explored as another strategy to re-establish self-tolerance. This approach has promise for the treatment of MS and, therefore, warrants further investigation. APLs are molecules in which the native encephalitogenic peptides are modified by substitution(s) of one or a few amino acids critical for contact with the TCR. Depending on the substitution(s) at the TCR contact residues of the cognate peptide, an APL can induce immune responses that can protect against or reverse EAE. However, the heterogeneity of the immune response in MS patients requires further study to determine which patients are most likely to benefit from APL therapy. Other potential approaches for vaccines in MS include vaccination against axonal growth inhibitors associated with myelin, use of dendritic cells pulsed with specific antigens, and active vaccination against proinflammatory cytokines. Overall, vaccines for MS represent promising approaches for the treatment of this devastating disease, as well as other autoimmune diseases.
多发性硬化症(MS)是一种中枢神经系统的炎性脱髓鞘疾病,其病理特征为血管周围浸润,主要由T细胞和巨噬细胞组成。尽管其病因尚不清楚,但有几条证据支持自身免疫机制在该疾病发展中起主要作用这一假说。几种广泛使用的疾病修饰药物已被批准用于治疗MS。然而,这些药物仅部分有效,目前尚不清楚它们减轻疾病更进展阶段的能力。因此,需要开发针对MS的改进治疗方案。本文综述了目前正在研究的几种新型选择性疫苗策略的作用,包括:(i)T细胞疫苗接种(TCV);(ii)T细胞受体(TCR)肽疫苗接种;(iii)DNA疫苗接种;以及(iv)改变肽配体(APL)疫苗接种。给予减毒的自身反应性T细胞可诱导调节网络特异性抑制MS中的致病性T细胞,这一策略称为TCV。TCV的概念基于针对传染病病原体的疫苗接种经验,即个体有意接触减毒的微生物病原体,然后指导免疫系统识别并中和其毒性形式。关于TCV,减毒的致病性T细胞同样用于指导免疫系统识别并中和致病T细胞。在实验性自身免疫性脑脊髓炎(EAE),一种MS的动物模型中,致病性T细胞使用数量惊人有限的可变区元件(V区)来形成针对特定自身抗原的TCR。因此,用针对这些TCR结构的肽进行疫苗接种可能诱导免疫调节机制,从而预防EAE。然而,与EAE不同,来自MS患者的髓鞘反应性T细胞利用广泛不同的V区,这对该方法的临床实用性提出了挑战。随后,将编码报告基因的质粒DNA注射到骨骼肌中导致编码蛋白的表达以及在自身免疫动物模型中诱导免疫反应这一现象被探索为重新建立自身耐受性的另一种策略。这种方法有望用于治疗MS,因此值得进一步研究。APL是通过替换与TCR接触至关重要的一个或几个氨基酸来修饰天然致脑炎性肽的分子。根据同源肽在TCR接触残基处的替换情况,APL可诱导免疫反应,从而预防或逆转EAE。然而,MS患者免疫反应的异质性需要进一步研究,以确定哪些患者最有可能从APL治疗中获益。MS疫苗的其他潜在方法包括针对与髓鞘相关的轴突生长抑制剂进行疫苗接种、使用用特定抗原脉冲处理的树突状细胞以及针对促炎细胞因子进行主动疫苗接种。总体而言,MS疫苗是治疗这种破坏性疾病以及其他自身免疫性疾病的有前景方法。